Vane controlled headlighting system



sea-#306 i ml m 3.3mm I BRBSSREFERENCE i Sept. 12, 1967 D. M. FINCH3,341,700

VANE CONTROLLED HEADLIGHTING SYSTEM Filed Oct. 19, 1964 5 Sheets-Sheet 1CENTER LINE INVENTOR. DAN M. FINCH ATTORNEY.

P 12, 1967 o. M. FINCH VANE CONTROLLED HEADLIGHTING SYSTEM 5Sheets-Sheet Filed Oct. 19, 1964 T R A R m R P INVENTOR.

DAN M. FINCH ATTORNEY CENTER LINE Sept. 12, 1967 D. M. FINCH VANECONTROLLED HEADLIGHTING SYSTEM 5 Sheets-Sheet 5 Filed Oct. 19, 1964INVENTOR.

DAN M. FINCH ATTORNEY Sept. 12, 1967 M. HN H 3,341,700

VANE CONTROLLED HEADLIGHTING SYSTEM Filed Oct. 19. 1964 5 Sheets-Sheet 4& 1-

FULL' SHADOW AREA} INVENTOR. DAN M. FINCH ATTORNEY.

Sept. 12, 1967 D. M. FINCH 3,341,700

VANE CONTROLLED HEADLIGHTING SYSTEM Filed Oct. 19, 1964 5 Sheets-Sheet 5CLEAR P OPAQUE OPAQUE CLEAR INVENTOR. DAN M. FINCH ATTORNEY.

United States Patent 3,341,700 VANE CONTROLLED HEADLIGHTING SYSTEM DanM. Finch, Berkeley, Calif., assignor to J. Page Hayden, Cincinnati, OhioFiled Oct. 19, 1964, Ser. No. 404,742 4 Claims. (Cl. 2407.1)

ABSTRACT OF THE DISCLOSURE Two head lamps project down the road beampatterns each having a light area and a shadow. The shadows blendwithout sharp transitional boundaries. Each head lamp comprises anelliptical reflector, a light source at the inner focal point of thereflector and a lens having its focus at the second focal point of thereflector, thereby to define an image region. A graded density filter islocated in light intercepting position in each image region. The filtershave fully light transmissive portions and light intercepting portionsand portions of intermediate transmissivities, and the last-mentionedportions' are so positioned that the shadows blend.

The present invention is an improvement in vane type headlightingsystems of the type which, although not limited thereto, generallyincludes elliptical reflector optics.

The statement of the objects of the invention and the problems which itsolves is prefaced by a brief discussion of elliptical reflector opticsand the like and vane type systems so that the environment in which suchproblems arose may be clearly understood.

The first vane system including elliptical-reflector type head lamps wasinvented by Evan P. Bone. It is shown and described in United StatesPatent 1,389,291, issued Aug. 30, 1921. The Bone system, as described inthis patent, and improvements to the Bone system extending over a periodof thirty years were directed to these 0bjectives: the production of afuller pattern of long range light for a car equipped with the system;and reduction of glare directed toward oncoming cars without sacrificinglight or visibility in the lane of the first-mentioned car, i.e. a Bonesystem-equipped car in which an observer is riding. Now making referenceto FIG. 2 (the upper part of which is isometric and the lower part ofwhich is in plane) the Bone system employs a pair of head lights, whichare installed on the front of an automobile. Each Bone head light (FIGS.2 and 9) comprises an optical projector. This projector consists of asealed beam ellipsoidal reflector, such as 20, provided with a singlefilament 21 placed at the rear focus of the reflector, whereby an imageof the filament appears at a plane 22. Plane 22 is the plane of theforward focus of the reflector and the plane of the rear focal point ofan aplanatic lens 23 disposed in front of plane 22. It will beunderstood that the aplanatic projection lens forms a narrow beam 24(FIG. 9) of approximately parallel rays and employs the projectedfilament image as a source. In accordance with the teachings of Bone,and as shown in the patents of Bone and/or associated workers, whichpatents are listed below, a movable vane 25 is mounted to move inlightintercepting fashion through plane 22. This vane, being at thefocal point of the projection lens 23, causes a sharp shadow 26 to beprojected along the road when the vane moves into the filament image onplane 22.

As shown in FIG. 2 the principal elements of the left hand head light(as seen by an observer in an equipped car) are referred to by thenumerals 20, 21, 25 and 23. The corresponding elements of the right handhead lamp are referred to by the numerals 27, 26, 29 and 30. The shadowproduced by the left hand head light is referred to by the numeral 26.As seen from the drivers seat of an equipped car as the point ofobservation, the shadow 26, 31 produced by the right hand head lamp,while overlapping shadow 26 for the most part, will extend to the right,across the center line, and into the drivers lane, by an amount d. Thequantity d is proportioned to the spacing D between the two head lamps,the aiming point for each head lamp, and the distance from the headlamps to the down-road point at which the registration is checked.

A light pattern about four times as wide as it is high is sought to beproduced by Bone head lamps. This is a considerably fuller beam patternthan is provided by standard head lamps during high beam operation, andthis pattern provides needed illumination above the level of the headlamps. Concomitant increase in candle power accomplishes a substantialimprovement in seeing distance. The Bone system, involving anellipsoidal reflector and a vane, therefore produces longer rangevisibility and a greatly improved light pattern. Increase of range ofvisibility and reduction of glare are simultaneously achieved.

Attention is now invited to several disadvantages and limitations of theBone type system. It has not been found feasible under all conditions tomake the two shadows 26, 31 and 26 register or coincide and to eliminatethe margin 31. Second, there is a sharp transition between highintensity and to low intensity light at the edges of the shadow as seenby the driver and the occupants of the equipped car. This sharptransition is objectionable to some drivers. Third, due to the fact thatit is not economically practical to use a color corrected lens chromaticabberation is present. Such aberration can produce spurious red or bluerays at the edge of the shadow. Finally, the prior art vane and opticshave no provisions for meeting current legal requirements.

In order that the full impact of these disadvantages may be betterunderstood, the discussion now proceeds to the dynamics of the vane.

As shown in FIG. 5, each lamp 32 normally projects a long range, highintensity light beam 36 down the road. When an oncoming car 34 (shown inFIG. 4) comes within range each of the equipped cars head lightscontinues to project a high intensity beam down the right side of theroad, but the opaque light intercepting vane 25 in the lamp 32, forexample, projects its image as a protective nonglare shadow 26 on theleft side of the road, modifying the beam distribution as shown by 33(FIG. 4). The oncoming driver sees very dim, relatively glare-free headlamps. It will be understood that two approximately coordinated shadowsare cast, one shadow for each head light.

The vane 25 (FIG. 2) is placed in the focal area of reflector 20whenever another car 34 (FIG. 4) approaches. This may be accomplishedmanually as by a foot switch or automatically as by a phototube controlcircuit. The present discussion postulates that the operation is binaryand not continuous. The vane alters the pattern of the light (FIG. 4) sothat a long range light pattern 33 and safe visibility are maintained inthe line of the equipped car and so that the shadow assures protectionagainst glare for oncoming drivers. The result is that the headlightingin ones own lane is equivalent to or greater than that of theconventional high beam, even when the equipped car is passing anoncoming vehicle. However, glare directed against oncoming drivers isonly a fraction of the glare experienced with standard down or lowbeams. As the approaching vehicles finish passing each other the FIG. 5

conditions are restored.

While the invention is described as including an ellipsoidal reflectorthe invention is applicable to systems in which the reflector is in forma slightly modified ellipse or is non-conical. Additionally, thelocation of the focal planes is not critical. The reflector element maybe moved away from the plane of the focal point of the lens.

Since the present invention is of utility in binary systems, eithermanual or automatic, and in automatic tracking systems, a fewdefinitions are now in order.

First, a distinction is made between a two-state or binary system and acontinuously operable or tracking system. A binary system has twodiscrete states of operation designated high beam and low beam. Theconventional automobile headlighting system of today is a binary system.A binary system may be either automatic or manual, i.e. eithercontrolled by a phototube (or equivalent) or foot-switched (orhand-switched). A tracking system is automatic and continuously followsan oncoming car in a manner which simulates the tracking motion of thehuman eye.

Conventional headlighting ot today does not employ vanes. Separatefilaments are conventionally provided for the high beam and low beammodes of operation. It is now in order to draw a distinction betweensuch conventional headlighting systems and vane type systems. A basiccontinuous vane type system and improvements thereto are shown in thefollowing United States patents:

2,562,258-Bone, Headlighting System, July 31, 1951 2,753,487-Bone,Headlight Control System, July 3, 1956 2,917,663-Engelmann,Synchronizing and Compensating Circuit for Headlight Control System,Dec. 15, 1959 2,917,666-Engelmann and Foster, Momentary ElectricalOverride for Headlight Control System, Dec. 15, 1959 2,941,117Dugle,Mechanically Steerable and Electronically Automatic Headlighting System,June 14, 1960 2,941,118--Engelmann, Vane Actuating Circuitry forHeadlighting System, June 14, 1960 3,132,252-Engelmann, PhotosensitiveAutomatic Headlight Control System, May 5, 1964 An illustration of anearly binary vane type system is the above-mentioned United StatesPatent 1,389,291 to Bone, issued Aug. 30, 1921.

In a continuously automatic system the shadows 26 and 26, 31 (FIGS. 2and 4) are projected down the road when an oncoming car comes withinpick-up distance. When the system is continuous and automatic thisshadow casting is automatically accomplished, so that the shadows justcover the oncoming car at all times. As the oncoming car approachescloser and closer, the generally overlapping shadows are automaticallymoved to the left, as viewed from the equipped car. As the cars pass theshadows are entirely removed from the road. The motions of the shadowsare continuous in an automatic tracking system. In a binary system,however, the shadows are intially cast by reason of a manual order givenby the vehicle operator. The shadows remain cast until the passing ofthe two cars is accomplished. whereupon the shadows are removed manuallyas by foot switching or the like. If the binary system is automatic thisis accomplished by the control of a phototube or the like.

While the present invention is described as incorporated in a binarysystem, it is reiterated that the invention is useful both in binary andcontinuously operable or tracking systems. The background of theinvention and the pertinent prior art and the problems raised by theprior art having been pointed out, the discussion now proceeds to theobjects of the invention.

A primary object of the invention is to provide, in a vane typeheadlighting system, a variable density (i.e. variable transmittance)vane, so proportioned that the beam pattern cast by vane controlled headlamps is made legally acceptable.

Another object of the invention is to provide in a vane controlled headlamp system, vanes of such character and construction that thedisadvantages heretofore occasioned by improper registration do notarise.

It is of course an object of the invention to eliminate the sharptransition which heretofore characterized the shadow edges.

A related object of the invention is to eliminate the objectionablechromatic aberration which accompanies said transition.

Another related object of the invention is to shape the left, rightand/or upper portions of the beam by controlling the intensity, usingthe variable transmittance vane to accomplish this shaping.

The importance of the object directed to improved registration isdemonstrated by various attempts made to solve the probelm, i.e. theelimination of margin 31 (FIG. 2). One proposal is shown in FIG. 3 ofDugle Patent 2,941,117, reproduced here as FIG. 10. In the Dugleproposal the head lamps are vertically stacked. That is, one group ofhead lamp elements as illustrated in FIG. 2 is placed above anothergroup of such head lamp elements. Accordingly the reference numerals ofFIG. 10 are primed to indicate that the FIG. 10 elements are generallysimilar to the FIG. 2 elements.

The head lamp vanes 29' and 25 are carried by the same shaft 37 on whicha direction finder vane 38 (presently described) is mounted. Vanes 25'and 29' are azimuthally positioned in synchronism. Light from anoncoming car passes through lens 39 to phototube 40 and causes vane 38automatically to be positioned in accordance with the teachings of BonePatent 2,753,487. The direction finder vane and the lamp vanes arepositioned by a photoelectrically controlled electronic circuit.

The pertinent aspect of FIG. 10 is the fact that the superposition orstacking of the head lights represents an attempt to solve theregistration problem. This approach is completely outside of thepractice and trends in automobile construction and styling. Theadvantage of the present system over the FIG. 10 solution resides inpart in its compatibility with automobile construction and the morecurrent trends in styling.

The parenthetical discussion of FIG. 10, necessary to a completeunderstanding of the objects of the invention, calls for a briefdiscussion of FIG. 6. FIG. 6 shows a Bone-type direction finderincluding a lens 39, a phototube 40, and a vane 38 azimuthallypositioned by a motor 41 automatically in accordance with the relativebearing of an oncoming car. The continuous type Bone system comprised adirection finder including photoelectric means such as 40, for detectingthe presence of an oncoming vehicle. The direction finder vane waspositioned in azimuth to measure the direction of approach of theoncoming vehicle. The head lamp vanes were coordinated with thedirection finder vane in such a way as to cast the overlapping shadowsor non-glare areas. Since in the prior art system of FIGS. 6 and 10 onelamp was superimposed 'on the other the undesired margin 31 of FIG. 2was effectively eliminated, but as previously indicated the solution haspractical drawbacks.

Another effort to solve the registration problem consists in thegeometric shaping of the right hand lamp vane in such a way as to makethe shadow which it casts corre spond to the shadow 26 (FIG. 2), thuseffectively eliminating margin 31. The disadvantage of this solutionresides in the fact that it is completely satisfactory only in operatingon relatively flat terrain and under that condi- 321111 53f car loadingfor which vane alignment was estabe An additional object of theinvention is to provide an arrangement such that the shadow approachesits FIG. 1 position by a motion downwardly and to the right, as viewedfrom an equipped car.

For a better understanding of the present invention, together with otherand further objects, advantages and capabilities thereof, reference ismade to the following description of the appended drawings, in whichthere is illustrated a preferred form of improved headlighting system inaccordance with the invention. In the drawings:

FIG. 1 is a pictorial illustration (the upper part being isometric, thelower part being in plan), generally schematic, showing means andmethods in accordance with the present invention and featuring a gradeddensity (variable transmittance) filter for projecting a protectiveshadow pattern down the road;

FIG. 2 is a pictorial view (the upper part being isometric, the lowerpart being in plan), generally schematic, showing how overlappingshadows were formed in accordance with the prior art vane practice;

FIG. 3 is a schematic top plan view showing the relative positions ofthe equipped car and two other cars under the FIG. 7 circumstances,together with a projected outline of the light intensity pattern of theequipped car;

FIGS. 4 and 5 are schematic outline drawings showing in plan theconditions which exist when an oncoming car is within the protectiveshadow (FIG. 4), and the conditions which exist when an oncoming car istoo remote to be picked up and protected by the shadow (FIG. 5),respectively;

FIG. 6 is a top plan view of a prior art direction finder;

FIG. 7 is a pictorial view as taken from the front seat of an equippedautomobile, showing an oncoming automobile, an automobile approachingfrom the right, and the light intensity characteristics of the shadowprojected down the road by the equipped car;

FIG. 8 is a plan or face view of a graded density filter in accordancewith the invention as seen by an observer looking into the headlamp fromthe front;

FIG. 9 is an outline drawing of the basic optics in a typical ellipticalheadlighting system in which the improved filter of the presentinvention may be installed; and

FIG. 10 is a cross-sectional view of a prior art head lamp and directionfinder as incorporated in a continuous type system, showing anenvironment in which head lamp vanes in accordance with the inventionmay be used;

FIG. 11 is a view of the mounted vane construction as viewed by anobserver in an oncoming car. The vane is arranged so that the shadowmoves downwardly to the right as seen from an equipped car (on adiagonal 30 to 45 from the horizontal) as the vane approaches its FIG. 1static position.

Attention is now invited generally to FIGS. 1, 3, 7 and 8 for adescription of the improvements made in accordance with the invention,and specifically to FIG. 1. The upper part of FIG. 1 is an isometric orperspective view showing a pair of head lamps incorporating improvedvane constructions provided by this invention. The elements 20, 21, 23,27, 28 and 30 of FIG. 1 are alike in construction and function to theelements to which have been assigned corresponding reference numerals inFIG.

2. That is, elements 20 and 27 are elliptical reflectors,

elements 21 and 28 are filaments, and elements 23 and 30 are aplanaticlenses. The reference numeral 54 collectively designates the elements ofthe equipped cars left head lamp.

It has previously been indicated that the utility of the presentinvention is not limited to purely elliptical reflectors or to theprecise arrangement of focal planes here shown.

From a point of observation in the drivers seat of the equipped car,elements 23 and 30 are the most forwardly located elements (i.e. theoccupant of the equipped car is behind elements 20 and 27, FIG. 1). Theequipped car is to the right of the center line and the shadow isgenerally to the left of the center line, as seen from such point ofobservation (i.e. the drivers seat of the equipped car).

The FIG. 1 arrangement in accordance with the invention differs from theprior art FIG. 2 system primarily in the incorporation of a variabledensity filter as shown generally in FIG. 1 and in detail in FIG. 8. Forpurposes of explanation, filter 42 is shown in FIG. 8 as comprising aclear area 43, a variable-density area 44, and an opaque area 45, withabrupt transitions 46 and 47 between the variousareas. These transitionsare imaginary and are utilized only as an expedient for cleardescription. In practice, as a point on area 43 is displaced in thedirections A and A as indicated in FIG. 8, the light transmittancegradually decreases and there is a gradual blend between areasdesignated by the reference numerals 43 and 44. Similarly, the densityat a point in area 44 gradually increases as it is displaced in thedirections A and A of FIG. 8. Likewise, the area 44 gradually andimperceptably blends into the area 45. The entire area 45 is opaque forall practical purposes. Generalizing, the approach from point P to pointQ is generally characterized by a change from approximately transparencyto approximately 0% transparency. The degree of transmittance at anypoint in the filter 42 is the ratio of the light intensity desired atthe corresponding point in the head lamp pattern to the maximum candlepower intensity which the head light can produce at that point.Therefore, given either the presently ordained and legally acceptedlight intensity pattern or any desired light intensity pattern, thetransmittance characteristics of the vane can readily be determined bythe simple use of the arithmetic of ratio and proportion.

In a preferred mode of making the vane 42, a metal coating can beevaporated onto a suitable high temperature resisting substrate such asglass or quartz. Means and methods for designing graded filters are perse well known.

Reference is now made to the single shadow 48 (FIG. 1) which iseffectively cast by a system according to the present invention andincorporating a graded density filter. In order to aid the explanationit is stated grossly that the region R of the shadow 48 corresponds tothe region R of the vane 42. The region Q, of the shadow corresponds toregion Q of the vane (still making reference to FIG. 1). The lines 49,50, etc. in FIG. 1 represent a variation in light intensity in the fielddue to the variation in the intensity in the filter in region 44 and maybe thought of crudely as corresponding to lines of constanttransmittance in the filter. That is to say, point X on line 50,slightly displaced away from a point Y on line 49, has a lesser lightintensity than point Y. Similarly, a point G on line 49 has a greaterlight intensity than a slightly displaced point H on line 50. In otherwords, there is no sharp frontal shadow edge but there is a gradualchange from light to shadow; nor is there any sharp side edge, but againthere is a gradual decrement from light to shadow. There being no sharptransitions and edges there are no radical discontinuities to register.When the gradually darkening regions or borders of one shadow aresuperimposed on the gradually darkening borders or regions of anothershadow, those regions blend together so smoothly and continuously as notto present any serious registration problem, with its concomitantdisadvantages and limitations. The lines 49 and 50 etc. (counting awayfrom the edges and toward the main body of the shadow) thereforerepresent a gradual approach to darkness, full shadow being achieved atthe inner line 51, which has a gross correspondence to line 47 of thevane (FIG. 8).

FIG. 3 and FIG. 7 represent substantially the same condition using headlamps on car 35 of the type shown in FIG. 1. Considering for the momentonly the left hand side of the picture, that is, the left lane and theoncoming car 34, FIG. 3 shows a single curve on the roadway which wouldcorrespond to line 49 in FIGS. 1 and 7. Consequently the region R ofFIG. 1 would appear in front of the oncoming car 34 in FIG. 3 and againin FIG. 7 while the region Q, of FIG. 1 will appear alongside oncomingcar 34 in FIG. 3 and again in FIG. 7. FIGS. 3 and 7 also show a car 52to the right of the roadway, stopped at the intersection of a sidestreet with the roadway. FIG. 7 indicates that the pattern of the headlamp on the right hand side of the road has been altered in a mannersimilar to the alteration on the left hand side. Such an alteration canbe readily accomplished by the introduction of additional areas such as44 and 45 of FIG. 8 but in the lower right hand corner of the vanerather than the lower left hand corner. An alternate means by which thedistribution on the right hand side of the road can be changed would bethe introduction of a second filter which would be used solely for thepurpose of protecting cars in the position of car 52. Such a secondfilter need not be introduced precisely in the plane 22 as shown in FIG.9, but may be introduced either slightly forward or slightly behind thatplane, there being a lack of chromatic aberration in either case asdiscussed below.

It will be apparent from the foregoing description that, by reason ofthe use of a graded density filter to grade the transmittancecharacteristics of the shadow borders, the resulting beam pattern can bemade to assume the shape indicated by M in FIGS. 3 and 7, the patternbeing the area enclosed by line 49. The sharp edges of shadows areeliminated, the heretofore noticeable non-register of the shadows castby the right and left hand lamps is rendered negligible and chromaticaberration is eliminated. The reason for the elimination of chromaticaberration is the absence of sharp transitions.

For purposes of illustration the vanes discussed herein are positionedin azimuth. In binary systems the head lamp vanes would beangularly-positioned in what could be called the flash or open roadposition (corresponding to high beam) for normal conditions ofoperation, with no oncoming car in sight. When an oncoming car is pickedup or approaches under circumstances normally calling for dimming ofhead lamps then the vanes are angularly positioned in the searchposition (corresponding to low beam). For a definition of What is meantby the expressions flash and searc reference is made to the UnitedStates patent of Richard H. Engelmann, No. 3,132,252, issued May 5,1964. Suflice it for the present to say that search generallycorresponds to dim and flash generally corresponds to bright" operationof head lamps. The search and flash overrides in said Engelmann patentand other patents referred to therein are both manual and binary,although they are included in continuous systems. Therefore variouselectronic systems for positioning the vanes are well known to thoseskilled in the art as is further evidenced by the expired Bone patentreferred to above, No. 1,389,291.

It has been the practice to move the shadow from left to right, as seenfrom an equipped car, as the shadow approaches the position illustratedin FIG. 1. Another improvement provided in accordance with theinvention, directed to the purpose of assuring compliance with legalrequirements, comprises means for introducing into the motion of thevane a vertical component. That is, the axis 55 of the vane, FIG. 11, istilted at an angle to the vertical. The FIG. 11 view of the vane and itsaxis of rotation 55 are taken from approximately the same point ofobservation as FIG. 1. Since the vane as shown in FIG. 11 moves at anangle to the horizontal (i.e., upwardly and to the right), as the vanemoves into intercepting position the shadow moves, as viewed by anobserver in an oncoming car, downwardly and to the left as it assumesthe position illustrated in FIG. 1. The angle of inclination of shadowmotion to the horizontal is preferred to be in the range from 30to 45degrees.

The diagonal motionof the shadow allows the driver I While there hasbeen shown and described what is at present considered to be thepreferred embodiment of the present invention, various modifications andchanges will occur to those skilled in the art, and it is intended inthe appended claims to secure the invention with a proper range ofequivalents.

Having described my invention, I claim:

1. The combination of a first head lamp for projecting a beam patternhaving a light area and a first shadow,

a second head lamp for projecting a beam pattern having a light area anda second shadow,

the first head lamp comprising a first reflector and a first lightsource and a first lens relatively positioned to define a first imageregion which receives all light from the first source which is reflectedby the first reflector, and the second head lamp comprising a secondreflector and a second light source and a second lens relativelypositioned to define a second image region which receives all light fromthe second source which is reflected by the second reflector, and gradeddensity filters individually located in light intercepting position insaid image regions, said filters having fully light transmissiveportions and light intercepting portions and portions of intermediatetransmissivities relatively so positioned that the shadows blend withoutsharp transitional boundaries.

2. A head lamp for projecting a beam pattern having a light area and ashadow and a gradual transition between the light area and the shadowcomprising, in combination:

an elliptical reflector having inner and outer focal a light sourcelocated in the region of said inner focal point,

a lens having a focus in the region of said outer focal point,

' said reflector and light source and lens being relatively positionedto define an image region, substantially at said outer focal point,which receives all light from the source which is reflected by thereflector, and

a graded density filter located in light intercepting position in saidimage region.

3. A head lamp in accordance with claim 2, in which the graded densityfilter has fully light transmissive portions and light interceptingportions and portions of intermediate transmissivities, and

means for introducing the light-intercepting portions of said filterinto said image region whereat the light intercepting portions introducesaid shadow into said pattern.

4. A head lamp in accordance with claim 3 in which the last-mentionedmeans first introduces the fully light transmissive portions and thenthe portions of intermediate transmissivities and finally the lightintercepting portions 'of the filter into said image region.

References Cited UNITED STATES PATENTS 1,480,803 l/1924 Bone 25041.32,603,133 7/1952 Strong 88-108 2,927,245 '3/ 1960 Iriand et al. .2315-83 2,979,601 4/ 1961 McClees 240-4649 3,132,252 6/1964 Engelmann250-214 JOHN W. HUCKERT, Primary Examiner. A. J. JAMES, AssistantExaminer.

1. THE COMBINATION OF A FIRST HEAD LAMP FOR PROJECTING A BEAM PATTERNHAVING A LIGHT AREA AND A FIRST SHADOW, A SECOND HEAD LAMP FORPROJECTING A BEAM PATTERN HAVING A LIGHT AREA AD A SECOND SHADOW, THEFIRST HEAD LAMP COMPRISING A FIRST REFLECTOR AND A FIRST LIGHT SOURCEAND A FIRST LENS RELATIVELY POSITIONED TO DEFINE A FIRST IMAGE REGIONWHCH RECEIVES ALL LIGHT FROM THE FIRST SOURCE WHICH IS REFLECTED BY THEFIRST REFLECTOR, AND THE SECOND HEAD LAMP COMPRISING A SECOND REFLECTORAND A SECOND LIGHT SOURCE AND A SECOND LENS RELATIVELY POSITIONED TODEFINE A SECOND IMAGE REGION WHICH RECEIVES ALL LIGHT FROM THE SECONDSOURCE WHICH IS REFLECTED BY THE SECOND REFLECTOR, AND GRADED DENSITYFILTERS INDIVIDUALLY LOCATED IN LIGHT INTERCEPTING POSITION IN SAIDIMAGE REGIONS, SAID FILTERS HAVING FULLY LIGHT TRRANSMISSIVE PORTIONSAND LIGHT INTERCEPTING PORTIONS AND PORTIONS OF INTERMEDIATETRANSMISSIVITIES RELATIVELY SO POSITIONED THAT THE SHADOWS BLEND WITHOUTSHARP TRANSITIONAL BOUNDARIES.